The present invention generally relates to excision and removal of tissue in surgical procedures, and more specifically to the use of fluid means for excising and removing tissue. In particular, the invention is directed toward the emulsification and removal of the lens of the eye to treat cataracts and similar disorders.
One state of the art technique for phacoemulsification involves the use of a pulsed fluid jet delivered through a small diameter cannula. An exemplary device for this purpose is disclosed in patent applications noted above and filed by the present inventor.
It has been determined that the application of hot water to a cataractus lens will more easily emulsify the lens, making it easier to aspirate the tissue through a small cannula. The optimum temperature for this purpose is in a range just below the boiling point of water. The introduction of hot water into the capsule containing the lens is a difficult and problematic task. The quantity of water must be very small, generally less than one milliliter, and well-controlled. Moreover, hot tubing or other structures for delivering heated water may damage eye tissue at any point of contact. Thus, it would seem prudent to heat the water at the point of delivery, thereby avoiding the potential for thermal damage to adjacent eye structures.
Likewise, temperature control of the heated water is critically important, particularly when operating in a temperature range that approaches the boiling point. If the water is heated at the point of delivery, the heat added to the mass of water must be proportional to the flow rate, so that a constant temperature is maintained. It is critical that this process be accurately controlled to avoid the generation of live steam at the point of delivery, which would be very damaging to the eye.
Thus, the restrictions for a heated water phacoemulsification instrument, include limited volume, constant elevated water temperature, and a cool delivery cannula. There is no device known in the prior art that is designed to emulsify and aspirate a lens using heated water, nor is there any device that is capable of meeting these stringent design criteria.